Throttle valve device and method for magnetizing the same

ABSTRACT

A throttle valve device includes a body, a valve, a motor, and a cover. The body defines a passage, a motor space, and a connecting portion that connects the motor space to the passage. The motor includes a motor yoke made of a magnetic material, a plurality of magnets that are arranged on an inner circumferential surface of the motor yoke. The plurality of magnets are magnetized in a state where the motor yoke is disposed in the motor space of the body. The plurality of magnets are arranged in a circumferential direction in the motor yoke with a space. The connecting portion is aligned with the space between the plurality of magnets in a radial direction of the motor yoke.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application, which claims thebenefit of priority from Japanese Patent Application No. 2019-155001filed on Aug. 27, 2019. The entire disclosure of all of the aboveapplication is incorporated herein by reference.

TECHNICAL FIELD

The disclosure in this specification relates to a throttle valve device,and the throttle valve device may be used as, for example, an electronicthrottle device for controlling intake air of an engine, an EGR valveused in an exhaust gas circulation system, an intake passage pressurecontrol valve for a diesel engine, and a negative pressure control valvefor controlling a hydrogen concentration of a fuel cell. The presentdisclosure particularly relates to a magnetized structure of a motorthat rotates a throttle valve.

BACKGROUND

In an electronic throttle device, for example, a motor yoke isresin-molded into a body using a magnetic resin material, and the moldedmagnetic resin motor yoke is magnetized by a magnetizing device.

SUMMARY

In one aspect of the present disclosure, a throttle valve deviceincludes a body, a valve, a motor, and a cover. The body defines apassage, a motor space, and a connecting portion that connects the motorspace to the passage. The valve is disposed in the passage and isconfigured to control a flow rate by adjusting a passage area of thepassage. The motor is disposed in the motor space and is configured togenerate a driving force for the valve to rotate. The cover covers anopen end of the body. The motor includes a motor yoke made of a magneticmaterial, a plurality of magnets arranged on an inner circumferentialsurface of the motor yoke, a motor shaft disposed inside the motor yoke,a pair of motor bearings rotatably support the motor shaft, an armaturecore coupled to the motor shaft in the motor yoke, a commutator coupledto the motor shaft in the motor yoke, a brush configured to energize thecommutator, a brush holder that holds the brush. The plurality ofmagnets are magnetized in a state the motor yoke is disposed in themotor space of the body. The plurality of magnets are arranged in acircumferential direction in the motor yoke with a space. The connectingportion is aligned with the space between the plurality of magnets in aradial direction of the motor yoke.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objectives, features andadvantages thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings.

FIG. 1 is a vertical cross-sectional view of an electronic throttle.

FIG. 2 is a front view of a body.

FIG. 3 is a front view of a cover.

FIG. 4 is a vertical cross-sectional view of a motor part.

FIG. 5 is a front view of a motor yoke.

FIG. 6 is a cross-sectional view of the motor yoke.

FIG. 7 is a front view of the motor yoke disposed in the body.

FIG. 8 is a cross-sectional view of the motor yoke disposed in the body.

FIG. 9 is a front view of a motor yoke according to a modified example.

FIG. 10 is a front view of the motor yoke according to a modifiedexample.

FIG. 11 is a cross-sectional view of the motor yoke according to themodified example.

FIG. 12 is a cross-sectional view of the motor yoke according to themodified example.

FIG. 13 is a cross-sectional view of a contact surface between the bodyand the motor yoke.

FIG. 14 is a cross-sectional view of the contact surface between thebody and the motor yoke.

FIG. 15 is a cross-sectional view of the contact surface between thebody and the motor yoke according to a modified example.

FIG. 16 is a cross-sectional view of the contact surface between thebody and the motor yoke according to a modified example.

FIG. 17 is a cross-sectional view showing a position of a slit of themotor yoke.

FIG. 18 is a cross-sectional view showing a position of the slit of themotor yoke.

FIG. 19 is a cross-sectional view of the motor yoke according to amodified example.

FIG. 20 is a cross-sectional view of the contact surface between thebody and the motor yoke.

FIG. 21 is a cross-sectional view showing a motor bearing of the cover.

FIG. 22 is a front view showing an example in which a slit is formed ina collar.

FIG. 23 is a cross-sectional view of the collar of FIG. 22 .

FIG. 24 is a cross-sectional view showing the motor bearing of the coveraccording to a modified example.

FIG. 25 is a cross-sectional view showing the motor bearing of the coveraccording to a modified example.

FIG. 26 is a cross-sectional view showing the motor bearing of the coveraccording to a modified example.

FIG. 27 is a cross-sectional view of a bearing space in the coveraccording to a modified example.

FIG. 28 is a rear view of the cover.

FIG. 29 is a cross-sectional view of the motor yoke.

FIG. 30 is a cross-sectional view taken along XXX-XXX in FIG. 29 .

FIG. 31 is a cross-sectional view showing a brush holder according to amodified example.

FIG. 32 is a front view of the motor yoke in which the brush holdershown in FIG. 31 is inserted.

FIG. 33 is a cross-sectional view taken along XXXIII-XXXIII in FIG. 32 .

FIG. 34 is a cross-sectional view showing a brush holder according to amodified example.

FIG. 35 is a partially enlarged view of FIG. 34 .

FIG. 36 is a cross-sectional view showing the motor yoke according to amodified example.

FIG. 37 is a cross-sectional view taken along XXXVII-XXXVII in FIG. 38 .

FIG. 38 is a cross-sectional view of the motor yoke and the brush holderaccording to a modified example.

FIG. 39 is a cross-sectional view of an example in which the brushholder is pressed into the body.

FIG. 40 is a cross-sectional view taken along the line XL-XL in FIG. 39.

FIG. 41 is a cross-sectional view showing a brush holder according to amodified example.

FIG. 42 is a front view of the motor yoke in which the brush holdershown in FIG. 41 is inserted.

FIG. 43 is a cross-sectional view taken along the line XLIII-XLIII inFIG. 42 .

FIG. 44 is a cross-sectional view showing a brush holder according to amodified example.

FIG. 45 is a partially enlarged view of FIG. 44 .

FIG. 46 is a cross-sectional view showing the body according to amodified example.

FIG. 47 is a cross-sectional view taken along the line XLVII-XLVII inFIG. 48 .

FIG. 48 is a cross-sectional view of the body and the brush holderaccording a modified example.

FIG. 49 is a cross-sectional view showing a brush holder according to amodified example.

FIG. 50 is a cross-sectional view showing the motor pinion and the brushholder according to a modified example.

FIG. 51 is a cross-sectional view showing the motor pinion and the brushholder according to a modified example.

FIG. 52 is a cross-sectional view showing the motor pinion and the brushholder according to a modified example.

FIG. 53 is a cross-sectional view showing a motor bearing of the body.

FIG. 54 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 55 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 56 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 57 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 58 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 59 is a right side view of FIG. 58 .

FIG. 60 is a cross-sectional view showing the motor bearing of the bodyaccording to a modified example.

FIG. 61 is a cross-sectional view showing the motor yoke according to amodified example.

FIG. 62 is a cross-sectional view showing the motor yoke according to amodified example.

FIG. 63 is a cross-sectional view enlarging and illustrating anintermediate shaft in FIG. 2 .

FIG. 64 is a cross-sectional view showing fixing of the intermediateshaft according to a modified example.

FIG. 65 is a front view of the body.

FIG. 66 is a front view of the cover.

FIG. 67 is a front view of the cover according to a modified example.

FIG. 68 is a perspective view of the cover in FIG. 67 .

FIG. 69 is a diagram showing directions of a reference pin of the coverin FIG. 67 .

FIG. 70 is a front view of the body.

FIG. 71 is a cross-sectional view showing a terminal.

FIG. 72 is a cross-sectional view showing a terminal according to amodified example.

FIG. 73 is a cross-sectional view showing a terminal according to amodified example.

FIG. 74 is a cross-sectional view showing a terminal according to amodified example.

FIG. 75 is a front view of an electronic throttle device.

FIG. 76 is a side view of the electronic throttle device.

FIG. 77 is a rear view of the electronic throttle device.

FIG. 78 is a diagram in which a magnetizing yoke is arranged in theelectronic throttle device in FIG. 76 .

FIG. 79 is a cross-sectional view taken along line LXXIX-LXXIX in FIG.75 .

FIG. 80 is a cross-sectional view taken along line LXXX-LXXX in FIG. 75.

FIG. 81 is an enlarged view of LXXXI portion in FIG. 79 .

FIG. 82 is a cross-sectional view taken along the line LXXXII-LXXXII ofFIG. 75 .

FIG. 83 is a cross-sectional view showing a body according to a modifiedexample.

DETAILED DESCRIPTION

To begin with, a relevant technology will be described only forunderstanding the following embodiments.

In an electronic throttle device, the motor yoke is resin-molded in astate where it is integrated with the body, and therefore the motor yokeis exposed to an outside without being covered by the body. Thisexternal exposure is desirable for magnetization, but since the magneticforce is transmitted to the outside after magnetization, a rotationangle sensor used for the electronic throttle device and other engineparts, especially a magnetic sensor or motor parts, might be adverselyaffected by the magnetic force.

Further, in the electronic throttle device, since the entire motor yokeis made of a magnetic resin material, it is physically impossible toform a space between magnetized magnets, and thus the magnetic circuitof the magnet might be insufficiently formed.

The present disclosure has been made in view of the above, and it is oneobjective to provide a motor structure where the magnet can bemagnetized after assembly of the body, the magnetic circuit can beappropriately formed, and magnetic leakage can be prevented.

As described above, in a first aspect of the present disclosure, athrottle valve device includes a body, a valve, a motor, and a cover.The body defines a passage, a motor space, and a connecting portion thatconnects the motor space to the passage. The valve is disposed in thepassage and is configured to control a flow rate by adjusting a passagearea of the passage. The motor is disposed in the motor space and isconfigured to generate a driving force for the valve to rotate. Thecover covers an open end of the body. The motor includes a motor yokemade of a magnetic material, a plurality of magnets arranged on an innercircumferential surface of the motor yoke, a motor shaft disposed insidethe motor yoke, a pair of motor bearings rotatably support the motorshaft, an armature core coupled to the motor shaft in the motor yoke, acommutator coupled to the motor shaft in the motor yoke, a brushconfigured to energize the commutator, a brush holder that holds thebrush. The plurality of magnets are magnetized in a state the motor yokeis disposed in the motor space of the body. The plurality of magnets arearranged in a circumferential direction in the motor yoke with a space.The connecting portion is aligned with the space between the pluralityof magnets in a radial direction of the motor yoke.

In this throttle valve device, when the magnet is magnetized, theconnecting portion of the body does not interfere with themagnetization. In addition, since the magnets have the spacetherebetween in the circumferential direction, a magnetic circuit can beproperly formed after the magnetization.

In a second aspect of the present disclosure, a thickness of a portionof the body corresponding to the motor space that houses the pluralityof magnets has a constant value in an axial direction.

Thus, in the throttle valve device, it is suitable for magnetizing themagnets through the body after assembling.

In a third aspect of the present disclosure, a thickness of a portion ofthe body corresponding to the motor space that houses the plurality ofmagnets has a constant value in a circumferential direction.

Thus, in the throttle valve device, it is suitable for magnetizing themagnets through the body after assembling.

In a fourth aspect of the present disclosure, a method for magnetizing athrottle valve device. The throttle valve device includes a body thatdefines a passage, a motor space, and a connecting portion that connectsthe motor space to the passage, a valve that is disposed in the passageand is configured to control a flow rate by adjusting a passage area ofthe passage, a motor that is disposed in the motor space and isconfigured to generate a driving force for the valve to rotate, and acover that covers an open end of the body. The motor includes a motoryoke made of a magnetic material, a magnet that is arranged on an innercircumferential surface of the motor yoke, a motor shaft that isdisposed inside the motor yoke, a pair of motor bearings that rotatablysupport the motor shaft, an armature core that is coupled to the motorshaft in the motor yoke, a commutator that is coupled to the motor shaftin the motor yoke, a brush that is configured to energize thecommutator, and a brush holder that holds the brush. The method includesa magnet arranging step of arranging the motor yoke in the motor spaceof the body and arranging the magnet in the motor yoke, and amagnetizing step of magnetizing the magnet disposed in the motor spaceof the body.

Since the magnet is arranged in the motor yoke, the magnetic circuit canbe well formed after the magnets are magnetized. Further, since themotor yoke is held in the body, magnetic leakage from the magnet can beeffectively prevented.

In a fifth aspect of the present disclosure, the magnet arranging stepfurther includes bringing one ends of a pair of magnets into contactwith a holding portion formed in the inner circumferential surface ofthe motor yoke, providing a holding spring in a space between the otherends of the pair of magnets, and biasing the pair of magnets against theholding portion by the holding spring.

Since the holding portion is interposed between the one ends of the pairof magnets and the holding spring is interposed between the other ends,a space can be formed between the magnets, and therefore the magneticcircuit is more properly formed.

In a sixth aspect of the present disclosure, the magnet arranging stepfurther includes arranging the magnet in a portion of the motor yoke andpress-fitting an outer circumferential surface of the portion of themotor yoke into the motor space of the body.

By reducing the space between the magnet and the motor yoke and betweenthe motor yoke and the body, the magnet can be effectively magnetized.

In a seventh aspect of the present disclosure, the magnetizing stepfurther includes providing a pair of magnetizing yokes at an outercircumferential surface of the body at a position corresponding to themotor space, and energizing the pair of magnetizing yokes.

Since the magnetizing yokes are close to the magnet via the body and themotor yoke, the magnet can be effectively magnetized.

In an eighth aspect of the present disclosure, the magnetizing step isperformed with the body having a constant thickness in a circumferentialdirection at a position facing the pair of magnetizing yokes.

The distance from the magnetizing yoke to the magnet has a constantvalue in the circumferential direction, and thus the magnet can beeffectively magnetized.

In a ninth aspect of the present disclosure, the magnetizing step isperformed with the body having a constant thickness in an axialdirection at a position facing the pair of magnetizing yokes.

The distance from the magnetizing yoke to the magnet has a constantvalue in the axial direction, and thus the magnet can be effectivelymagnetized.

In a tenth aspect of the present disclosure, the magnetizing step isperformed with the magnet that is positioned within an area definedbetween two lines connecting ends of the pair of magnetizing yokes thatface each other.

It is possible to equally magnetize the entire magnet and to effectivelyutilize the magnetizing yoke.

In an eleventh aspect of the present disclosure, the magnet magnetizedby the method according to the above-described aspects.

Hereinafter, an embodiment in which the present disclosure is applied toan electronic throttle device will be described below with reference tothe drawings. As described above, the present disclosure can be widelyused as a throttle valve device such as an EGR valve, a diesel engineintake passage pressure control valve, and a fuel cell negative pressurecontrol valve. Therefore, the names of the throttle shaft, the throttlevalve, and the like are used because the present disclosure is appliedto the electronic throttle device, but such uses of the shaft and thevalve are not necessarily limited to the throttle.

FIG. 1 is a vertical cross-sectional view of the electronic throttledevice. An outline of the electronic throttle device 1 will be describedwith reference to FIG. 1 . The electronic throttle device 1 is arrangedin an engine compartment and controls a flow rate of an intake air takeninto an engine. An engine control unit (not shown) calculates an optimumintake amount in accordance with driver's accelerator pedal operations,an engine rotation state, and the like, and outputs a rotational amountaccording to the calculation results to the motor 100.

The motor 100 is disposed in a motor space 330 of a body 300, and therotation of the motor 100 is transmitted to a reduction mechanism 200via a motor pinion 102 that is press-fitted and fixed to a motor shaft101. As shown in FIG. 2 , in the reduction mechanism 200, large-diameterteeth 202 on an intermediate gear 201 meshes with the motor pinion 102.The intermediate gear 201 is held to be rotatable about an intermediateshaft 203. The intermediate shaft 203 is press-fitted and fixed into afitting hole 301 of the body 300.

Small-diameter teeth 204 on the intermediate gear 201 meshes with teeth211 formed in an arc shape on an outer circumferential surface of thevalve gear 210, and the rotation of the motor pinion 102 is transmittedto the valve gear 210 via the intermediate gear 201. Therefore, thereduction mechanism 200 includes the motor pinion 102, thelarge-diameter teeth 202 and the small-diameter teeth 204 of theintermediate gear 201, and the teeth 211 of the valve gear 210. Thereduction rate is set such that when the motor shaft 101 rotates 28times, the one tooth 211 of the valve gear 210 advances clockwise orcounterclockwise.

Semicircular arc-shaped magnets 220 and 221 are arranged in an innercircumference of a cup-shaped center portion 212 of the valve gear 210,and the magnets 220 and 221 form a magnetic circuit. A disk-shaped lever401 is disposed in a deep portion (the right side in FIG. 1 ) of thecup-shaped center portion 212 of the valve gear 210. The magnets 220 and221 and the lever 401 are insert-molded with the valve gear 210.

The lever 401 is fixed to an end of the throttle shaft 402 by swaging.Therefore, the valve gear 210 is connected to the throttle shaft 402 viathe lever 401, and the rotation of the valve gear 210 is transmitted tothe throttle shaft 402. A disc-shaped throttle valve 400 is fixed to thethrottle shaft 402 by screws 403, and the throttle valve 400 increasesor decreases the opening area of an intake passage 320 formed in thebody 300 in accordance with the rotational position thereof.

An open end 303 (the left side in FIG. 1 ) of the body 300 is coveredwith a cover 500. The cover 500 is formed of a resin such as polybutylterephthalate, and as shown in FIG. 3 , ribs are formed at specifiedlocations to increase its strength. A pair of rotation angle sensors510, which are Hall ICs, are disposed in the cover 500 at positionscorresponding to the axis of the throttle shaft 402. The rotation anglesensor 510 is fixed to the cover 500. However, the pair of arc-shapedmagnets 220 and 221, which are insert-molded with the valve gear 210,are disposed on an outer circumference of the rotation angle sensor 510.Then, the magnets 220, 221 rotate about the shaft axis of the throttleshaft in accordance with the rotation of the throttle shaft 402.Accordingly, the magnetic circuit is moved to a position correspondingto the rotation angle of the throttle valve 400. The rotation anglesensor 510 detects the change in the magnetic force caused by the changein the magnetic circuit, and thus detects the opening degree of thethrottle valve 400. Then, the detected position information is fed backto an engine control unit (not shown).

The throttle shaft 402 is rotatably supported in the body 300 bybearings 405 and 406 disposed on both sides of the throttle valve 400.The bearing 405 is a plain bearing, and the bearing 406 is a ballbearing. An opening 302 of the body 300 for the throttle shaft 402 is anopening for the bearing 405 to be inserted and is covered by the plug310.

A space 321 for housing the valve gear 210 is formed in the body 300,and a coil ring 450 for urging the throttle shaft 402 is disposed inthis space 321. The coil spring 450 has a cylindrical shape, and bothends thereof are bent and protrude radially outward. The both ends ofthe coil spring 450 are locked to a locking surface of the body 300 anda locking surface of the valve gear 210 with a predetermined preload. Itshould be noted that 460 and 461 indicate guides disposed on both sidesof the coil spring 450, and the guides 460, 461 guide the torsionalmovement of the coil spring 450.

When the force of the motor 100 is not transmitted to the valve gear210, the biasing force of the coil spring 450 holds the throttle valve400 at an intermediate position to close the intake passage 320.However, at this intermediate position, the intake passage 320 is notfully closed so that a predetermined amount of intake air can flow intothe intake passage 320 and the vehicle can travel to evacuate when afailure occurs.

When the throttle valve 400 is rotated to the fully open position fromthe intermediate open position, one spring end of the coil spring 450 islocked to generate a biasing force in a returning direction, and themotor 100 rotates the throttle shaft 402 against the biasing forcetoward the returning side.

On the contrary, when the throttle valve 400 is rotated from theintermediate open position to the fully closed position, the otherspring end of the coil spring 450 is locked and an urging force in anopening direction is generated. Then, the motor 100 rotates the throttleshaft 402 against the biasing force in the opening direction.

Next, the structure of the motor 100 constituting the electronicthrottle device 1 will be described in detail.

As shown in FIG. 4 , the motor yoke 110 has a cylindrical shape withboth ends being open. The motor yoke 110 is formed by bending acold-rolled steel having a thickness of about 1 to 2 mm. Since aconventional motor yoke was formed into a cup shape by deep-drawing, 10or more molding dies had been required. Therefore, the number of moldingprocesses was increased, which resulted in an increase in amanufacturing cost. On the contrary, since the motor yoke 110 of thisexample is formed by bending a flat plate material, the molding processis facilitated, the manufacturing cost can be reduced, and the materialcost can be decreased.

At the bending process, as shown in FIGS. 5 and 6 , a slit 111 having apredetermined length is formed between both ends of the motor yoke 110.Then, as shown in FIGS. 1 and 4 , the body 300 is press-fitted into themotor space 330 from the open end 303. The deep side of the motor space330 has a small-diameter portion 311 for press-fitting, and an end ofthe small-diameter portion 311 and/or an end surface 112 of the motoryoke 110 is tapered to be smoothly press-fit. The press-fitting pressesthe motor yoke 110 and closes the slit 111 as shown in FIGS. 7 and 8 .

Although the slit 111 has a linear shape in the example of FIG. 5 , itis needless to say that the slit 111 may have another shape. Forexample, a zigzag-shaped slit 1111 may be used as shown in FIG. 9 , or anested slit 1112 may be used as shown in FIG. 10 . With the zigzag slit1111 of FIG. 9 , the motor yoke 110 can be positioned in the axialdirection and the circumferential direction, and the shape of the flatplate material that is bent into a cylindrical shape can be stable. Onthe other hand, in the nested slit 1112 in FIG. 10 , the motor yoke 110can be regulated in both directions for reducing and expanding thediameter of the motor yoke 110, and thus the cylindrical shape can bestable.

The cross-sectional shape of the motor yoke 110 is not necessarilylimited to the cylindrical shape as shown in FIG. 6 , and may be a trackshape having flat portions 116 as shown in FIG. 11 . With the trackshape, the position of the motor yoke 110 in the rotational directioncan be regulated, and thus the positions of the magnets 120 disposed inthe arc portion 117 can be easily set. Therefore, when magnetizing themotor yoke 110 and the magnets 120 after both are assembled to the body,the relative positions of the magnetizing yoke and the magnets 120 canbe properly set.

Further, in the above-described examples of FIGS. 1, 4, and 7 , themotor yoke 110 is brought into contact with an innermost surface 312 ofthe motor space 330 of the body 300 to position the motor yoke 110 inthe axial direction. Alternatively, as shown in FIG. 12 , a positioningyoke flange 118 may be formed at an end of the yoke 110 on the side ofthe open end 303, and the yoke flange 118 may be brought into contactwith the open end 303 of the body 300 to be positioned in the axialdirection. Since electric components such as a commutator 130 and abrush holder 140 are disposed in the body 300 at a position close to theopen end 303, the positioning accuracy can be improved by the yokeflange 118.

The yoke flange 118 is formed after bending the flat plate and thenwelding both end surfaces of the plate to form the motor yoke 110 into acylindrical shape. The yoke flange 118 may also be formed by molding anend portion of the cylindrical material when the motor yoke 110 is madefrom the cylindrical material.

When it is difficult to obtain high accuracy in the positioning by theinnermost surface 312 of the motor space 330 of the body 300, a step 313for positioning may be formed in the body 300 and the end surface 112 ofthe motor yoke 110 may be brought into contact with the step 313, asshown in FIG. 13 . However, if a certain positioning accuracy can besecured with a jig or the like, the motor yoke 110 is just press-fittedinto the small-diameter portion 311 of the body 300, and a gap may beformed between the innermost surface 312 of the body 300 and the endsurface 112 of the motor yoke 110. In the example of FIG. 14 , only apart of the motor yoke 110 in the axial direction is press-fitted intothe body 300. Hence, the press-fitting load can be reduced anddeformation of the motor yoke 110 during press-fitting can be avoided.

In the above example, the press-fitting of the motor yoke 110 isperformed at the deep side of the motor space 330 of the body 300.However, the motor yoke 110 may be press-fitted at a position where themagnet 120 is disposed as shown in FIG. 15 . Rather, the press-fittingat the position where the magnet 120 is disposed can eliminate the gapbetween the motor yoke 110 and the body 300. When the magnets 120 areassembled to the body 300 and then the magnets 120 are magnetized, sincethe gap between the body 300, the motor yoke 110, and the magnets 120 isthe smallest, an air gap also becomes small, the magnetic flux at thetime of magnetization is increased, and the motor performance can beimproved. Therefore, the press-fitting at the position of the magnets120 is preferable. In this case, a reduced diameter portion 315 isformed in a region of the motor space 330 of the body 300 correspondingto the magnets 120, and an end of the reduced diameter portion 315and/or the end surface 112 of the motor yoke 110 is tapered. As aresult, it is possible to realize smooth press-fitting of the motor yoke110.

As shown in FIG. 16 , the reduced diameter portion 315 of the body 300may be formed only in a region of the motor space 330 corresponding tothe magnets 120 in the circumferential direction. With this structure,when the magnets 120 are attached to the body 300 and then magnetized,the air gap becomes small, the magnetic flux at the time ofmagnetization is improved, and the motor performance can be improvedbecause the gap between the body 300, the motor yoke 110, and themagnets 120 is the smallest. In addition, the contact area between themotor yoke 110 and the body 300 in the circumferential direction isreduced, the press-fitting load can be reduced, and the deformation ofthe motor yoke 110 during press-fitting can be avoided.

From the viewpoint in forming a magnetic circuit, the above-mentionedslit 111 may interfere with the magnetic circuit and may be notdesirable. Therefore, when the slit 111 is necessarily formed, the slit111 should be located at a position covered by the magnet 120 as shownin FIG. 17 . This makes it possible to prevent the magnetic circuit frombeing blocked by the slit 111.

Since the rotation angle sensor 510 described above detects therotational position of the throttle valve 400 based on the magneticforces of the magnets 220 and 221, it is not desirable that the magneticforce from the magnet 120 leaks out through the slit 111. Therefore,when the slit 111 is necessarily formed, as shown in FIG. 18 , the slit111 should be disposed on a back surface of the magnet 120 and at aposition as far as possible away from the rotation angle sensor 510.

Further, in the example of FIG. 12 , the yoke flange 118 is formed inthe motor yoke 110 close to the body open end 303. However, as shown inFIG. 19 , a yoke bottom portion 119 may be formed at the body innermostsurface 312. By forming the yoke bottom portion 119, the strength of themotor yoke 110 can be increased, the load generated when the motor yoke110 is press-fitted into the body 300 can be increased, and the holdingpower by the motor yoke 110 can be increased. In order to form the yokeflange 118 and the bottom portion 119, a bent plate material is welded,or a cylindrical material is used for the motor yoke 110 and the yokeflange 118 and the bottom portion 119 is formed at an end of thecylindrical material. As a result, the slit 111 can be prevented.

Further, in the above example, the motor yoke 110 covers the armaturecore 150 and the brush holder 140. However, the axial length of themotor yoke 110 may be shortened to cover only the armature core 150.Further, as shown in FIG. 20 , the motor yoke 110 may have a length tocover only the magnets 120.

Among the functions of the motor yoke 110, the function as a framemember to hold the motor shaft 101 may be performed by the body 300.However, the body 300 is not suitable to form a magnetic circuit sincethe body 300 is made of a die-cast material of aluminum. Therefore, themotor yoke 110 made of an iron material is required at the portion tocover the magnets 120. The example of FIG. 20 is an example in which themotor yoke 110 is used with a required minimum amount.

Returning to FIGS. 1 and 4 , the armature core 150 is press-fitted intothe motor shaft 101, and the motor coil 151 is wound around the armaturecore 150. The motor coil 151 faces the magnets 120 while the armaturecore 150 is arranged inside the motor yoke 110. The commutator 130 isalso press-fitted into the motor shaft 101, and the brush holder 140 isarranged to cover the commutator 130. A carbon brush 141 held by thebrush holder 140 is pressed against the commutator 130 by a spring, andpower is supplied to the brush 141.

The above-described motor pinion 102 is press-fitted into the motorshaft 101 at a position closer to the open end 303 than the commutator130. Then, the motor shaft 101 is rotatably supported by the motorbearings 160 and 161 at both ends thereof. One of the motor bearings 160is a sintered metal impregnated with oil, and the motor bearing 160 ispress-fitted into the motor space 330 through a motor opening 331 thatis in communication with the motor space 330 of the body 300. Then, themotor opening 331 is sealed by the motor plug 332.

The other of the motor bearings 161 is also a sintered metal impregnatedwith oil, and is held by a collar 163 disposed in the bearing space 520of the cover 500. In addition, since the cover 500 is made of polybutylterephthalate and there is a risk of insufficient strength as describedabove, the collar 163 is disposed in the cover 500. The collar 163 maybe made of metal such as iron, stainless steel or aluminum, or may bemade of thermosetting resin such as epoxy resin or phenol resin.

Note that either one or both of the motor bearings 160 and 161 may be aball bearing instead of using the sintered metal impregnated with oil.

In this example, since both ends of the motor shaft 101 are supported bythe motor bearings 160 and 161, the rotation support can be favorablyperformed. Particularly, in comparison with a conventionally usedexample in which the motor bearing is arranged between the motor pinion102 and the commutator 130, the motor pinion 102 of this embodiment isinterposed between the motor bearing 161 and the commutator 130. Thus,the motor pinion 102 can prevent foreign matter such as abrasion powderof the brush 141 from reaching the motor bearing 161.

If the motor bearing 161 is made of a sintered metal impregnated withoil, the oil may leak from the motor bearing 161 due to swelling of theoil at a high temperature. However, since the motor pinion 102 ispresent as in this embodiment, it is possible to effectively prevent theleaked oil from flowing toward the commutator 130.

The collar 163 may have any shape as long as it fits into the bearingspace 520 of the cover 500, and may have a cylindrical shape as shown inFIG. 21 . Since the width of the motor bearing 161 is about 5 mm, thecollar 163 may have a width equal to or greater than the width of themotor bearing 161. If the collar 163 has a cylindrical shape as shown inFIG. 21 , insertion of the collar 163 into the bearing space 520 can beeasily done by forming a color slit 164 as shown in FIGS. 22 and 23 .

The shape of the collar 163 may be a bottomed cylindrical shape as shownin FIG. 24 . With this shape, the strength of the collar 163 can beincreased. In addition, the cylindrical shape with a bottom makes itpossible to integrally insert-mold the collar 163 together with thecover 500. That is, the bottom portion 165 of the collar 163 can preventa resin generated during injection molding of the cover 500 from flowinginto the bearing space 520.

As shown in FIG. 25 , the shape of the collar 163 may be a bottomedcylindrical shape with a collar flange 166, i.e., a top hat shape. Thecollar flange 166 further increases the strength of the collar 163, andinsert molding is facilitated.

Further, as shown in FIG. 26 , a step portion 167 may be formed in thecollar 163 and the motor bearing 161 may be positioned by the stepportion 167 in the axial direction. By having the motor bearing 161 incontact with the step portion 167, the positional accuracy of the motorbearing 161 is improved.

The portion of the cover 500 where the collar 161 is disposed requires acertain strength. Therefore, the portion of the cover 500 is formed as athick portion. On the other hand, weight saving for the cover 500 isalso required. Therefore, as shown in FIG. 27 , a thick portion 502 maybe formed in only a circumferential area of the bearing space 520 andthe remaining portion may be formed as a thin portion 503. Since theload applied to the motor bearing 161 is supported by the thick portion502, bending due to the deformation of the resin can be avoided. Thethin portion 503 is formed with ribs 501 at appropriate positions tohave necessary strength.

Further, in the above-mentioned example, the bearing space 520 of thecover 500 is formed by protruding away from the body 300. However, asshown in FIG. 27 , a surface opposite to the body 300 may be formed as aflat surface. By making this surface flat, it is possible to suppresswraparound of the resin injected when the collar 163 is insert-molded.As a result, welds caused by such resin wraparound are less likely tooccur, and the strength of the cover 500 is improved.

Further, as shown in FIG. 28 , a gate 505 for injecting resin may beformed at the center of the bearing space 520 of the cover 500. As aresult, generation of welds around the collar 163 can be suppressed.

FIG. 29 shows a cross-section of the motor, and the brush holder 140 ispress-fitted into the motor yoke 110. In particular, as shown in FIG. 30, the brush holder 140 is press-fitted so that the entire circumferencethereof comes into contact with the inner surface of the motor yoke 110.

In this example, as shown in FIGS. 29 and 30 , since the entire outercircumference of the brush holder 140 is covered with the motor yoke 110and therefore there is no gap therebetween, foreign matter can beeffectively prevented from entering the commutator 130 or the armaturecore 150. The foreign matter includes abrasion powders and the like fromthe coil spring 450 arranged above.

In addition, since the brush holder 140 is press-fitted into an open endof the motor yoke 110 and fixed over the entire circumference thereof,positional accuracy of the brush holder 140 is improved. As a result,the accuracy of assembly of the brush holder 140 with the mating cover500 is also improved. As a result, fitting between the terminals 143,144 of the brush holder 140 and the terminals 530, 531 formed in thecover 500 is also improved.

Further, since the positional accuracy of the brush holder 140 isimproved, the positional accuracy of the brush 141 is also improved. Asa result, the pressing force by the brush 141 against the commutator 130is stabilized, the slidability of the brush 141 is improved, and therotation torque of the motor 100 is reduced. At the same time, the brush141 and the commutator 130 are smoothly in contact with each other, andhunting due to vibration of the brush 141 is suppressed.

As shown in FIG. 31 , the brush holder 140 may have a step portion 145formed on the outer circumference thereof, and the positioning stepportion 145 may be brought into contact with an tip end 113 of the motoryoke 110. Accordingly, the tip end 113 at the open end of the motor yoke110 is covered by the brush holder 140, and the effect of preventingforeign matter from entering is further improved. In addition, thepositional accuracy of the brush holder 140 in the axial direction isfurther improved, and the axial lengths of both the brush 141 and thecommutator 130 can be minimum lengths, which leads to downsizing of theelectronic throttle device 1.

FIG. 32 is a front view of the motor yoke 110 in which the brush holder140 shown in FIG. 31 is inserted. FIG. 33 shows a cross-section takenalong the line XXXIII-XXXIII of the motor yoke 110 of FIG. 32 . Tworecesses 114 are formed in the motor yoke 110. Two positioningprotrusions 142 are fitted into the two recesses 114, and the motor yoke110 and the brush holder 140 are positioned in the rotational direction.

In this example, in addition to press-fitting of the brush holder 140over the entire circumference thereof, positioning in both the axialdirection and the radial direction is performed. As a result, thepositioning can be made more accurate, the fitting of the terminal canbe improved as described above, the contact with the commutator can bemade smoothly due to the improved positional accuracy of the brush, andthe electronic throttle device 1 can be further downsized. However,although it is desirable to provide the recesses and the protrusions forregulating the rotation as in this example, positioning can be done evenin the example of FIG. 30 by using the terminals 143 and 144.

FIG. 34 is a cross-sectional view showing a modified example of thebrush holder 140. As in this example, an annular recess 146 may beformed in the brush holder 140, and the tip end 113 of the motor yoke110 at the open end may be press-fit into the annular recess 146. Sincethe resin brush holder 140 and the metal motor yoke 110 have differentcoefficients of thermal expansion, the brush holder 140 having a greatercoefficient of thermal expansion has a larger deformation depending ontemperature. As shown in FIG. 35 , even if the brush holder 140thermally contracts at a low temperature, an outer surface 147 of theannular recess 146 comes into close contact with the outercircumferential surface of the motor yoke 110 to prevent foreign matterfrom entering. On the contrary, even if the brush holder 140 thermallyexpands at a high temperature, an inner surface 148 of the annularrecess 146 comes into close contact with an inner circumferentialsurface of the motor yoke 110, and foreign matter is also prevented fromentering.

As shown in FIG. 36 , a positioning protrusion 1101 may be stamped andformed on the motor yoke 110, and a surface of the brush holder 140close to the armature core 150 may be brought into contact with theprotrusion 1101. The protrusion 1101 can provide more accuratepositioning.

In the example of FIG. 36 , the protrusion 1101 is brought into contactwith the surface of the brush holder 140 close to the side of thearmature core 150. However, as shown in FIG. 37 , a slit 149 may beformed on an outer circumferential surface of the brush holder 140 andprotrusion 1101 may be press-fit into the slit 1101. By engaging theprotrusion 1101 with the slit 149, the brush holder 140 can bepositioned in the circumferential direction.

Since the brush holder 140 is press-fitted into the motor yoke 110 inthe axial direction, the protrusion 1101 comes in contact with the endsurface 1491 of the slit 149 during press-fitting as shown in FIG. 38 .In the example of FIG. 38 , the protrusion 1101 and the slit 149 areengaged with each other, whereby the brush holder 140 can be positionedin both the circumferential direction and the axial direction.

In the above example, the brush holder 140 is press-fitted into themotor yoke 110, but it may be press-fitted into the body 300 instead ofthe motor yoke 110. As described in the example of FIG. 20 , the motoryoke 110 minimally requires a portion facing the magnets 120, and thusthe motor yoke 110 may eliminate a portion facing the brush holder 140.In this case, as shown in FIG. 39 , the brush holder 140 is directlypress-fitted into the body 300.

Even if the brush holder 140 is directly press-fitted into the body 300in this way, the brush holder 140 is in close contact with the body 300over the entire circumference thereof as shown in FIG. 40 and preventsforeign matter from entering toward the armature core 150. Thepositioning accuracy improved by bringing the entire outercircumferential surface of the brush holder 140 into close contact isthe same as that of pressing into the motor yoke 110 shown in FIGS. 29and 30 .

When press-fitting the brush holder 140 into the body 300, the brushholder 140 may be provided with a positioning step 145 as shown in FIG.41 so that the step 145 comes into contact with the open end 303 of thebody 300 during press-fitting. This contact makes it possible to coverthe body 300, prevent the intrusion of foreign matter, and improve thepositional accuracy, as with the example described in the example ofFIG. 31 .

A positioning protrusion 142 may be formed in the brush holder 140 andfitted into a positioning recess 304 formed on the body 300 as shown inFIGS. 42 and 43 . This further improves the positioning accuracy in boththe axial direction and the circumferential direction, as with theexamples of FIGS. 32 and 33 .

Further, as shown in FIG. 44 , an annular recess 146 may be provided inthe brush holder 140, and an annular protrusion 305 of the body 300 maybe fitted into the annular recess 146. As shown in FIG. 45 , the gapbetween the annular recess 146 and the opening 306 of the motor space330 of the body 300, which may be generated due to thermal contractionor thermal expansion, can be eliminated by the annular recess outersurface 147 or the annular recess inner surface 148 of the brush holder140, which is similar to the example of FIGS. 34 and 35 .

As shown in FIG. 46 , a protrusion 306 may be formed in the body 300,and the end face of the brush holder 140 may be brought into contactwith this protrusion 306 to secure axial positioning. Alternatively, asshown in FIG. 47 , the protrusion 306 may be fitted into the slit 149 ofthe brush holder 140 to secure circumferential positioning. Furthermore,as shown in FIG. 48 , the protrusion 306 may be fitted into the slit 149to secure both axial and circumferential positioning. These are similarto the examples of FIGS. 36 to 38 .

In FIG. 39 , the brush holder 140 is press-fitted into the body 300 witha gap between the motor yoke 110 and the brush holder 140. However, thebrush holder 140 may be brought into contact with an end surface of themotor yoke 110 to be positioned in the axial direction. In this case, itis not necessary to form a protrusion or the like for positioning thebrush holder 140 in the axial direction, and therefore its structure canbe simplified.

Although the examples of FIGS. 39 to 48 show only the peripheral portionof the inner motor yoke 110 of the body 300, the shape of the body 300is, as shown in FIG. 1 , is a vertically elongated shape having theintake passage 320 in the upper side and the motor space 330 in thelower side, and only a part around the motor space 330 is illustrated.The motor space 330 has a cylindrical shape in accordance with the shapeof the motor yoke 110. The annular protrusion 305 of FIGS. 44 and 45 isformed to protrude at a position around the motor yoke 110 in the motorspace 330 of the body 300.

In the example described above, foreign matter is prevented fromentering by the outer circumferential surface 1401 of the brush holder140 which is brought into close contact with the motor yoke 110 or thebody 300. However, as shown in FIG. 49 , a predetermined gap between theinner circumferential surface 1402 of the brush holder 140 and the motorshaft 101 may be formed so as not to interfere with rotation of theshaft 101. Therefore, an annular cover member 1403 is formed in thebrush holder 140, and an outer circumference of the motor pinion 102 iscovered with the cover member 1403 to form an intricate structure, whichprevents foreign matter from entering toward the commutator 130.

In the example of FIG. 49 , the motor pinion 102 includes a pinionportion where the pinion gear 103 is formed and a cylindrical portion104 where no gear is formed, and the cover member 1403 faces the innercylindrical portion 104 of the motor pinion 102. Therefore, the gapbetween the cover member 1403 and the cylindrical portion 104 constantlyextends, which is desirable as an intricate structure. However, as shownin FIG. 50 , the pinion gear 103 may be formed over the entire length ofthe motor pinion 102, and even in this case, the effect of preventingforeign matter om entering by the intricate structure can be obtained.

Further, as shown in FIGS. 50 and 51 , the inner circumferential surfaceof the cover member 1403 may be an inner circumferential surface 1402 ofthe brush holder. As described above, abrasion powders of the coilspring 450 have been described as an example of the foreign matter.However, even with the intricate structure having only the cover member1403, the gap between the cover member 1403 and the motor pinion 102 canbe small, and thus the foreign matter intrusion prevention effect can beobtained.

As shown in FIG. 52 , a trap groove 1404 may be formed on the innercircumferential surface of the cover member 1403 of the brush holder140, and a trap groove 105 may be formed on the outer circumferentialsurface of the cylindrical portion 104 of the motor pinion 102. Then, anintricate structure may be formed by offsetting both the grooves 1404,105 from each other. Accordingly, foreign matter that has entered thegap between the cover member 1403 and the motor pinion 102 can becaptured by the trap grooves 1404 and 105.

A plurality of trap grooves 1404 and 105 may be formed on both the covermember 1403 and the motor pinion 102, and alternatively, a plurality oftrap grooves 1405, 105 may be formed on only one of the cover member1403 and the motor pinion 102.

In the above example, the foreign matter invasion prevention effect forthe brush holder 140 of the motor yoke 110 has been described. In thepresent example, the motor yoke 110 is open at the deep side of themotor yoke 110 (i.e., the right side in FIG. 1 ), and therefore themotor bearing 160 is directly supported by the body 300.

Here, since the motor 100 is a single heat source for the electronicthrottle device 1, the temperature of the motor 100 can be higher thanan ambient temperature by 5 to 10° C. This is because the motor 100frequently repeats rotation based on signals from an engine control unit(not shown), the motor 100 always receives a force from the coil spring450 in order to hold the throttle valve 400 at a predetermined position,and a driving force for obtaining a certain torque is required.

Since the electronic throttle device 1 is arranged in the enginecompartment of the vehicle, the ambient temperature greatly varies froma low temperature when starting the engine during a severe winter seasonto a high temperature when operating the engine with a high speed duringmidsummer. However, in any situation, the motor 100 has the highesttemperature in the electronic throttle device 1.

In this example, heat generated in the motor coil 151 can be radiateddirectly to the body 300 via the motor shaft 101 and the motor bearing160, and thus heat radiation can be improved. In particular, since themotor bearing 160 is press-fitted into the body 300, the contact areabetween the motor bearing 160 and the body 300 is expanded, whichcontributes to the improvement of heat radiation.

Further, heat generated in the motor coil 151 and transferred to themotor yoke 110 can also be radiated directly to the body 300, therebyimproving the heat radiation performance of the motor 100. Since themotor yoke 110 is also directly press-fitted into the body 300, thecontact area can be expanded and therefore the heat radiation can beimproved similar to the motor bearing 160.

As shown in FIG. 53 , a bearing engaging portion 333 is formed betweenthe motor space 330 of the body 300 and the motor opening 331, and axialpositioning for the motor bearing 160 can be achieved by coming intocontact with bearing engaging portion 333. Since the motor opening 331is formed in the die-cast body 300 by cutting, the bearing engagingportion 333 can also be formed accurately. Therefore, by abutting themotor bearing 160 against the bearing locking portion 333, positionalaccuracy of the motor bearing 160 also increases. In addition, thecontact area between the motor bearing 160 and the body 300 is enlarged,which contributes to the improvement of heat radiation.

Further, when the motor bearing 160 is a sintered metal impregnated withoil, the swelling of the oil at a high temperature may flow out.However, the bearing engaging portion 333 can prevent the oil fromentering the motor space 330 toward the motor coil 151.

As shown in FIG. 54 , the motor opening 331 of the body 300 may have astepped shape, the motor bearing 160 may be disposed in a small diameterportion 3311 and the motor plug 332 may be disposed in a large diameterportion 3312. In this case, the motor bearing 160 can be crimped andfixed at the stepped portion of the motor opening 331. By crimping, evenwhen a fixing force between the body 300 and the motor bearing 160 bypress-fitting decreases due to thermal expansion or the like, the motorbearing 160 can be reliably held.

Further, as shown in FIG. 55 , the motor plug 332 may be brought intocontact with the motor bearing 160. In this case, the motor plug 332 canprevent the motor bearing 160 from being displaced. In this case, it isdesirable to provide a recess 3321 at a position of the motor plug 332facing the motor shaft 101 to prevent interference with the motor shaft101 by the motor plug 332.

As described above, the motor bearings 160 and 161 may beoil-impregnated sintered metal or ball bearings. FIG. 56 shows anexample in which the motor bearing 160 is a ball bearing. Such a ballbearing can also radiate heat from the motor shaft 101 to the body 300.

Further, as shown in FIG. 57 , a bearing support portion 334 forsupporting the motor bearing 160 in the body 300 may be formed as athick portion. By increasing its thickness in this way, heat transferredto the motor bearing 160 from the motor shaft 101 can be effectivelyradiated to the body 300. In addition, since the motor bearing 160 ismore firmly supported, loosening can be prevented. In addition, it ispossible to suppress deformation of the motor opening 331 of the body300 when the motor plug 332 is press-fitted.

Instead of increasing the rigidity of the bearing support portion 334 bythickening the bearing support portion 334, ribs 3341 may be formed inthe bearing support portion 334 as shown in FIGS. 58 and 59 . The ribs3341 also increase the rigidity of the bearing support portion 334 andprevent the motor bearing 160 from loosening. Further, since the ribs3341 increase a heat radiation area of the bearing support portion 334,the heat radiation performance can be further improved.

In the example described above, the motor bearing 160 is press-fittedthrough the motor opening 331 of the body 300 to assemble the motorbearing 160. However, as shown in FIG. 60 , a bearing engaging portion335 may be formed in the body 300, and the motor bearing 160 may bepress-fitted from the motor space 310. In this example, the motorbearing 160 is brought into contact with the bearing engaging portion335 to be positioned in the axial direction. Since the bearing engagingportion 335 has a stepped shape, interference with the motor shaft 101can be avoided.

Further, in the above-mentioned example, the motor bearing 160 ispress-fitted into the body 300 to improve the heat radiation performancefor the motor 100. However, as shown in FIG. 61 , a bearing supportportion 1190 may be formed by forming the bottom 119 of the motor yoke110 into a protruding shape. By directly holding the motor bearing 160in the motor yoke 110, the relative positional accuracy between themotor yoke 110 and the motor bearing 160 can be improved. In the exampleof FIG. 61 , since the shape of the motor yoke 110 is complicated, themotor yoke 110 is formed by being drawn from a plate material.

Further, as shown in FIG. 62 , the motor yoke 110 may be bent and thebottom portion 119 may have a concave shape so that a bearing supportportion 1191 is formed. Accordingly, the relative position accuracy ofthe motor yoke 110 and the motor bearing 160 is improved. Further, ifthe motor bearing 160 is a sintered metal impregnated with oil, theswelling of the oil at a high temperature may flow out. However, thebearing support portion 1191 can prevent the oil from entering the motorspace 330 toward the motor coil 151.

Next, an assembly process of the electronic throttle device 1 of thepresent embodiment will be described.

First, assembly of the motor 100 will be described. The motor shaft 101is press-fitted into the armature core 150 and the commutator 130, andthe motor coil 151 is wound in the slot of the armature core 150 using awinding machine so as to form a sub-assembly.

Then, the motor yoke 110 is formed in a cylindrical shape, and a holdingportion 1102 (FIG. 80 ) for holding the arc-shaped magnets 120 is formedon the motor yoke 110 to protrude inward. Then, the magnets 120 arearranged inside the motor yoke 110, and the magnets 120 are pressedagainst the holding portion 1102 by a spring 605 (see FIG. 79 , FIG. 80) to form a sub-assembly.

At the same time, a spring that presses the two brushes 141 toward thecommutator 130 is attached to the brush holder 140 in which theterminals 143 and 144 are insert-molded or press-fitted to form asub-assembly.

Since the assembly to the body 300 is always performed from onedirection, the motor bearing 160 is press-fitted through the motoropening 331 of the body 300, and then the body 300 is turned over. Afterturning over, the sub-assembly of the motor yoke 110 is press-fittedinto the motor space 330 of the body 300 from the open end 303. At thistime, after the motor yoke 110 is press-fitted into the body 300, themagnets 120 and the spring 605 for pressing the magnets 120 may beassembled.

Next, the sub-assembly in which the armature core 150 and the like areconnected to the motor shaft 101 is attached from the open end 303, andthe motor shaft 101 is supported by the motor bearing 160. After that,sub-assembly of the brush holder 140 is press-fitted to close the openend of the motor yoke 110. Next, the motor pinion 102 is connected tothe motor shaft 101. When the motor pinion 102 is connected, the motorshaft 101 is supported by the motor opening 331.

Next, the cover 500 having the motor bearing 161 is attached, the openend 303 of the body 300 is closed, then the body 300 is returned overagain, and the motor opening 331 is closed by the motor plug 332. Thecover 500 is attached in accordance with assembly of the valve gear 210and the intermediate gear 201, which will be described below.

Although the above is the preferable assembling process of the motor100, the process can be appropriately changed. For example, the magnets120 may be disposed in the motor yoke after the motor yoke 110 ispress-fitted into the body 300.

Next, assembly of the throttle shaft 402 and the valve gear 210 will bedescribed.

First, the bearing 406 is connected to the throttle shaft 402 at apredetermined position to form a sub-assembly. Further, the bearing 405is press-fitted from the opening 302 of the body 300. Next, the body 300is turned over, the sub-assembly of the throttle shaft 402 and thebearing 406 is inserted into the body 300 and is supported by thebearing 160, and then the bearing 406 is press-fitted into the body 300.Thereafter, the throttle valve 400 is fixed to the throttle shaft 402with the screws 403.

Then, the spring gear sub-assembly, which is formed by attaching theguides 460, 461 to the coil spring 450, and the valve gear 210 areattached from the open end 303 of the body 300. The valve gear 210 isfixed to the throttle shaft 402 by swaging the lever 401 which isinsert-molded on the valve gear 210.

Next, assembly of the intermediate gear 201 will be described.

First, the intermediate shaft 203 is press-fitted into the fitting hole301 of the body 300, and then the press-fitted intermediate shaft 203 isloosely fitted into the intermediate gear 201. Then, the cover 500 isattached to the body 300 so that the intermediate shaft 203 is fittedinto the guiding hole 506 of the cover 500 having the rotation anglesensor 510, and the open end 303 of the body 300 is closed. Thereafter,the body 300 is turned over again and the opening 302 is closed by theplug 310.

The outline of the assembling process is as described above, and theassembling of the body 300 and the cover 500 in this example will befurther described in detail below.

In this example, as shown in FIG. 2 , a positioning reference hole 307is formed in an area of the body 300 around the inner motor 100. On theother hand, as shown in FIG. 3 , a positioning reference pin 507 that isfitted into the positioning reference hole 307 is formed in the cover500 to protrude. Further, as described above, when the cover 500 isattached to the body 300, the intermediate shaft 203 also engages withthe guiding hole 506 of the cover 500.

Screw holes 3001, 3002, 3003, 3004 are formed at four corners of thebody 300, and bolt holes 5001, 5002, 5003, 5004 are also formed at fourcorners of the cover 500 at positions facing the corresponding screwholes 3001, 3002, 3003, 3004. In the bolt holes 5001, 5002, 5003, and5004 of the cover 500, metal collars are insert-molded to securestrength of the holes when bolt fastening.

In an assembling process of the body 300 and the cover 500, temporaryassembly is performed. That is, the positioning reference pin 507 of thecover 500 is fitted into the positioning reference hole 307 of the body300, and the intermediate shaft 203 of the body 300 is engaged with theguiding hole 506 of the cover 500. After the temporary assembly, bolts4000 are screwed into the screw holes 3001, 3002, 3003, 3004 of the body300 through the bolt holes 5001, 5002, 5003, 5004 of the cover 500,thereby completing the final assembly (see FIGS. 75 and 77 ).

When the bolts 4000 are tightened during the final assembling processafter the temporary assembly, a slight positional deviation isinevitably generated between the body 300 and the cover 500. However, inthis example, the clearance between the positioning reference hole 307of the body 300 and the positioning reference pin 507 of the cover 500is set to be smaller than the clearance between the intermediate shaft203 of the body 300 and the guiding hole 506 of the cover 500.Therefore, the positional deviation is absorbed by the guiding hole 506slightly moving around the positioning reference pin 507.

In a comparative structure, the positioning reference pin is formed atposition around the valve gear 210. This is to increase the detectionaccuracy of the rotation angle sensor 510, but since the positioningaccuracy at a position close to the valve gear 210 (i.e., an upperportion in FIG. 3 ) is increased, the positioning accuracy at a positionclose to the motor 100 (i.e., a lower portion in FIG. 3 ) is decreased.

On the contrary, in this example, since the positioning reference pin507 is formed at a position close to the motor 100, the positioningaccuracy of the portion close to the motor 100 is increased, and thedeviation at the fitting portion between the terminals 530 and 531 ofthe cover 500 and the terminals 143 and 144 of the motor 100 can bereduced. As a result, the terminals 530 and 531 of the cover 500 and theterminals 143 and 144 of the motor 100 have a better contact condition,and the wear resistance between both terminals is improved.

Although the positioning accuracy of the portion close to the motor 100is improved, the positioning accuracy of the portion close to the valvegear 210 is expected to decrease. However, the accuracy of the rotationangle sensor 510 may be compensated by correcting the outputcharacteristic from the rotation angle sensor 510 with software.

FIG. 63 illustrates with emphasis the relationship between theintermediate shaft 203 and the guiding hole 506 of the cover 500, but agap “c”, or a third gap, with several microns to several tens of micronsin size is inevitably formed between the intermediate shaft 203 and theguiding hole 506. As described above, the gap c allows the positionaldeviation between the temporary assembly and the final assembly bybolt-fastening. It is also possible to absorb by the gap c thedifference in thermal expansion due to the difference in thermalexpansion coefficient.

The minute gap c may be formed between the fitting hole 301 of the body300 and the intermediate shaft 203. Although FIG. 64 illustrates withemphasis to show this gap c, the gap c is about several tens of micronsor less in size. In the example of FIG. 64 , the intermediate shaft 203is loosely fitted into the fitting hole 301, and conversely, is tightlypress-fitted into the guiding hole 506 of the cover 500. Theintermediate shaft 203 may be insert-molded on the cover 500.

However, the temporary assembly of the body 300 and the cover 500 may beperformed as long as the intermediate shaft 203 and the reference pin507 formed in the motor 100 are used. Thus, as shown in FIGS. 65, 66 ,the clearance between the shaft 203 and the guiding hole 506 of thecover 500 may be set to be smaller than the clearance between thepositioning reference hole 307 of the body 300 and the positioningreference pin 507 of the cover 500. Since the center of positioning inthis case substantially matches the center of the body 300 and the cover500, both the positioning accuracy around the motor 100 (the lower sidein FIG. 65 ) and the positional accuracy around the valve gear 210 (theupper side in FIG. 65 ) can be improved.

As emphasized in FIGS. 67 and 68 , the reference pin 507 formed in themotor 100 may have an elliptical shape, and the reference hole 307corresponding to the reference pin 507 may be formed as a circle havinga diameter larger than the major axis of the reference pin 507. In thiscase, as shown in FIG. 69 , the major axis direction of the ellipticalreference pin 507 is desirably perpendicular to a line I1 connecting thecenter point 2031 of the intermediate shaft 203 and the center point3071 of the positioning reference hole 307 of the body. In other words,the positioning reference pin 507 has a first length in a directionalong the line I1 and a second length in a direction perpendicular tothe line I1. Then, the first length is shorter than the second length.This makes it possible to reduce the size of a minute gap (a gap “b”, ora second gap, shown in FIG. 69 ) in the tangential direction (or aperpendicular direction) perpendicular to the line I1 (a gap “a”, or afirst gap, as shown in FIG. 69 ). As a result, the difference in thermalexpansion due to the difference in coefficient of thermal expansionbetween the body 300 and the cover 500 can be absorbed by the large gapa, and the rotation of the cover 500 during bolt-fastening after thetemporary assembly is appropriately restricted by the small gap b in thetangential direction (or the perpendicular direction).

In the example of FIG. 69 , since the reference pin 507 is resin-moldedintegrally with the cover 500, it is easy to form the reference pin 507in an elliptical shape, and since the reference hole 306 is formed byexcavating the body 300, a circular inner diameter can be accuratelyformed.

In the example of FIG. 69 , the shape of the reference pin 507 is anelliptical shape, but the shape may have any shape as long as thediameter in the direction along the line I1 is shorter than the diameterin the perpendicular direction.

Furthermore, contrary to the above example, the reference pin may beformed in the body 300, and the reference hole may be formed in thecover 500. In this case, a fitting hole is formed in the body 300, andthe reference pin is fitted into the fitting hole. As described above,this modification in which the reference pin is formed in the body 300and the reference hole is formed in the cover 500 is not necessarilylimited to the example of FIG. 69 , and can be applied to the examplesof FIGS. 2 and 3 .

When it is premised that the assembly of the cover 500 is slightlyrotated about the intermediate shaft 203 located at the center, theshapes of the terminals 143 and 144 in the motor 100 and the terminals530, 531 in the cover 500 can also be set to match the shape of thecover 500.

Although FIG. 71 shows the terminal 143 in the motor 100, its shape isthe same of the terminal 144 in the motor 100 and the terminals 530, 531in the cover 500. That is, the terminals 143, 144 in the motor 100 orthe terminals 530, 531 in the cover 500 have a tuning fork shape asshown in FIG. 71 , and the remainders of the terminals 143, 144 or theterminals 530, 531 have a plate shape that can be fitted into the tuningfork shape of the terminals.

In the following description, it is assumed that the terminals 143 and144 in the motor 100 have a tuning fork shape, and the terminals 530 and531 in the cover have a plate shape, and description for the terminalshape will be described based on the terminal 143.

The terminal 143 has a tuning fork shape, and a pair of engagingportions 1431 and 1432 are formed at a tip end thereof. Engaging bodies1433 and 1434 protrude from the engaging portions 1431 and 1432 at theirtip ends, and a holding space 1436 is formed between the engaging bodies1433 and 1434 and a root portion 1435.

The gap 1437 between the engaging bodies 1433 and 1434 is smaller thanthe thickness of the terminal 530 by several tens of microns to 0.1 mm.Therefore, when the terminal in the motor 100 and the terminal in thecover 500 are engaged with each other, the engaging portions 1431 and1432 of the tuning fork-shaped terminal are pushed open and theplate-shaped terminal is held in the holding space 1437. The engagementbetween the terminal in the motor 100 and the terminal in the cover 500is maintained by the spring force caused by the elastic deformation ofthe engaging portions 1431 and 1432 of the tuning fork-shaped terminal.

A recess 14001 is formed in the brush holder 140 to prevent the rootportion 1435 of the terminal 143 from being buried in the brush holder140. Therefore, even if the engaging portions 1431 and 1432 are pushedopen at the time of engagement, stress due to deformation of theterminal 143 is not directly applied to the brush holder 140, andtherefore durability of the brush holder 140 is improved.

In this example, the terminal in the motor 100 and the terminal in thecover 500 are arranged so that the terminals have thickness directionsthat are perpendicular to each other. As shown in FIG. 70 , theterminals 143 and 144 in the motor 100 are arranged such that thethickness directions thereof are parallel to the line I connecting theintermediate shaft 203 and each of the terminals 143 and 144. Therefore,the terminals 530 and 531 in the cover 500 are arranged such that thethickness directions thereof are perpendicular to the line connectingthe guiding hole 506 and the terminals 530 and 531.

With such an arrangement, even if a slight amount of misalignment occursbetween the body 300 and the cover 500 during bolt-fastening, it ispossible to efficiently prevent the pair of engaging portions 1431 and1432 from being pushed open by the misalignment.

The shape of the terminal can be changed in various ways. As shown inFIG. 72 , a stepped portion 1438 may be formed in the terminal 143 toincrease the width of the engaging portions 1431 and 1432. By the stepportion 1438, the positioning of the terminal 143 with respect to therecess 14001 of the brush holder 140 becomes accurate. Further, as shownin FIG. 73 , a step portion 1439 may be formed to reduce the width ofthe engaging portions 1431 and 1432. In this case, the step portion 1439forms a space around the root portion 1435 so that it is not necessaryto form the recess 14001 in the brush holder 140 as shown in FIG. 71 .

The shapes of the cover 500 and the brush holder 140 can also bevariously changed. As shown in FIG. 74 , a cylindrical protector 5301that covers the periphery of the plate-shaped terminal 530 may beformed. By inserting a tip of the protector 5301 into the brush holder140 up to near the step portion 1439 of the terminal 143, the terminals143 and 530 can be covered, and foreign matter caused by abrasionpowders of the coil spring 450 can be prevented from reaching theterminals 143 and 530.

In the above example, the body 300 and the cover 500 are fixed by thebolts 4000 (see FIGS. 75 and 77 ), but other fixing members such asrivets and clips may be used instead of the bolts 4000.

FIGS. 75 to 77 show a state in which the electronic throttle device 1 isassembled by the above-described assembly process. The body 300 has theopen end 303 with a rectangular shape similar to the cover 500, and theopen end 303 is bolted to the cover 500. Both the space 330 and theintake passage 320 in which the throttle valve 400 is disposed have acylindrical shape. The cylindrical shape that serves as the motor space330 and the cylindrical shape that serves as the intake passage 320 areseparate from each other, and the both spaces 330 and 320 are partiallyconnected by a connecting portion 360.

As shown in FIGS. 11, 17 and 18 , the two magnets 120 are arranged inthe motor yoke 110, and a specified space is defined between one magnet120 and the other magnet 120. In this example, the magnets 120 arearranged on the left and right sides of the motor space 310 as shown inFIG. 11 . Therefore, the space between the two magnets 120 correspondsto the connecting portion 360 of the body 300. In other words, as shownin FIGS. 75 and 77 , the magnets 120 arranged in the motor space 330 ofthe body 300 are not blocked by the connecting portion 360. That is, theconnecting portion 360 is aligned with the space between the two magnets120 in a radial direction of the yoke 110 (see FIG. 79 ).

At the time of assembling of the electronic throttle device 1, themagnets 120 are not magnetized in order to facilitate the assemblingprocess, and are magnetized by a pair of magnetizing yokes 600 and 601after the assembling. The pair of magnetizing yokes 600 and 601 aredisposed corresponding to the pair of magnets 120, respectively, asshown in FIG. 78 . More specifically, as shown in FIG. 79 showing across-sectional view taken along LXXIX-LXXIX line in FIG. 75 and in FIG.80 showing a cross-section view taken along LXXX-LXXX line in FIG. 75 ,end surfaces 602, 603 of the magnetizing yokes 600, 601 have an arcshape in accordance with the shape of the motor space 330 of the body300, and can face the magnets 120 without interference by the connectingportion 360 of the body 300.

As shown in FIGS. 79 and 80 , one end of each of the arc-shaped magnets120 is in contact with a holding portion 1102 of the motor yoke 110, anda holding spring 605 is arranged at the other end of each of the magnets120. The magnets 120 are biased by the holding spring 605 against theholding portion 1102 to be held at a desired position.

Although not shown, coils are wound around the magnetizing yokes 600,601. By applying a large current to the coil, the yokes 600, 601 getelectro-magnetized, and the magnets 120 are magnetized by the magneticforce at that time of supplying the current.

As shown in FIG. 81 showing an enlarged view of LXXXI portion in FIG. 79, each of the magnets 120 is arranged within an area 6001 defined by twoline 6000 connecting both ends of the magnetizing yokes 600 and 601. Inaddition, the thickness of the motor space 330 of the body 300 has aconstant value at the portion facing the magnetizing yokes 600 and 601.Therefore, the magnets 120 can be magnetized uniformly. As describedabove, the connecting portion 360 of the body 300 is positioned within aregion 6002 which is spaced away from the magnetizing yokes 600 and 601.

Further, as shown in FIG. 82 showing a cross-sectional view taken alongthe line LXXXII-LXXXII of FIG. 75 , the constant thickness of the motorspace 330 of the body 300 is maintained even in the axial directionfacing the magnetizing yokes 600 and 601. In addition, the widths of themagnetizing yokes 600 and 601 are longer than an axial width 1201 ofeach of the magnets 120. This also makes it possible to achieve equal(or uniform) magnetization of the magnet 120.

As described above, the magnets 120 can be sufficiently magnetized evenafter they are housed in the body 300 made of aluminum. However, ifnecessary, a portion of the body 30 corresponding to the inner magnets120 may be cut out. FIG. 83 shows an example in which two windows areformed in the body 30 so that the magnetizing yokes 600 and 601 candirectly face the motor yoke 110. Since the motor yoke 110 is exposed tothe yokes 600, 601, the magnetizing efficiency by the magnetizing yokes600 and 601 can be improved.

What is claimed is:
 1. A throttle valve device, comprising: a body thatdefines a passage, a motor space, and a connecting portion that connectsthe motor space to the passage; a valve that is disposed in the passageand is configured to control a flow rate by adjusting a passage area ofthe passage; a motor that is disposed in the motor space and isconfigured to generate a driving force for the valve to rotate; and acover that covers an open end of the body, wherein the motor includes: amotor yoke made of a magnetic material; a plurality of magnets that arearranged on an inner circumferential surface of the motor yoke; a motorshaft that is disposed inside the motor yoke; a pair of motor bearingsthat rotatably support the motor shaft; an armature core that is coupledto the motor shaft in the motor yoke; a commutator that is coupled tothe motor shaft in the motor yoke; a brush that is configured toenergize the commutator; and a brush holder that holds the brush, theplurality of magnets are magnetized in a state where the motor yoke isdisposed in the motor space of the body, the plurality of magnets arearranged in a circumferential direction in the motor yoke, a space isdefined between the plurality of magnets in the circumferentialdirection, wherein the space is different from the inherent gap that isbetween each one of the plurality of magnets, and the connecting portionis aligned with the space defined between the plurality of magnets in aradial direction of the motor yoke.
 2. The throttle valve deviceaccording to claim 1, wherein a thickness of a portion of the bodycorresponding to the motor space that houses the plurality of magnetshas a constant value in an axial direction.
 3. The throttle valve deviceaccording to claim 2, wherein a thickness of a portion of the bodycorresponding to the motor space that houses the plurality of magnetshas a constant value in a circumferential direction.
 4. The throttlevalve device according to claim 1, wherein a thickness of a portion ofthe body corresponding to the motor space that houses the plurality ofmagnets has a constant value in a circumferential direction.
 5. A methodfor magnetizing a throttle valve device, the throttle valve deviceincluding: a body that defines a passage, a motor space, and aconnecting portion that connects the motor space to the passage; a valvethat is disposed in the passage and is configured to control a flow rateby adjusting a passage area of the passage; a motor that is disposed inthe motor space and is configured to generate a driving force for thevalve to rotate; and a cover that covers an open end of the body,wherein the motor includes: a motor yoke made of a magnetic material; amagnet that is arranged on an inner circumferential surface of the motoryoke; a motor shaft that is disposed inside the motor yoke; a pair ofmotor bearings that rotatably support the motor shaft; an armature corethat is coupled to the motor shaft in the motor yoke; a commutator thatis coupled to the motor shaft in the motor yoke; a brush that isconfigured to energize the commutator; and a brush holder that holds thebrush, the method comprising: a magnet arranging step of arranging themotor yoke in the motor space of the body and arranging the magnet inthe motor yoke; and a magnetizing step of magnetizing the magnetdisposed in the motor space of the body, wherein the magnet arrangingstep further includes: bringing one ends of a pair of magnets intocontact with a holding portion formed in the inner circumferentialsurface of the motor yoke; providing a holding spring in a space betweenthe other ends of the pair of magnets; and biasing the pair of magnetsagainst the holding portion by the holding spring.
 6. The methodaccording to claim 5, wherein the magnet arranging step furtherincludes: arranging the magnet in a portion of the motor yoke; andpress-fitting an outer circumferential surface of the portion of themotor yoke into the motor space of the body.
 7. The method according toclaim 5, wherein the magnetizing step further includes: providing a pairof magnetizing yokes to face an outer circumferential surface of thebody corresponding to the motor space; and energizing the pair ofmagnetizing yokes.
 8. The method according to claim 5, wherein themagnetizing step is performed with the body having a constant thicknessin a circumferential direction at a position facing the pair ofmagnetizing yokes.
 9. The method according to claim 5, wherein themagnetizing step is performed with the body having a constant thicknessin an axial direction at a position facing the pair of magnetizingyokes.
 10. The method according to claim 5, wherein the magnetizing stepis performed with the magnet that is positioned within an area definedbetween two lines connecting ends of the pair of magnetizing yokes thatface each other.
 11. A throttle valve device comprising: the magnetmagnetized by the method according to claim 5.